There has been known a single-molecule assay as a method for carrying out various assays by observing biomolecules such as proteins and nucleic acids in such a manner that the biomolecules are individually identified. In order to carry out the single-molecule assay, there have been known some methods.
Patent Literature 1 discloses a micro chamber for detecting single-molecule enzyme activity. This micro chamber includes a container part into which a liquid droplet can be sealed and which has capacity of storing a liquid droplet of up to 1000 fL (femtoliters). The container part is made of a recess provided in at least one of a first member and a second member which are bonded to each other. According to Patent Literature 1, an enzyme reaction is carried out in the liquid droplet. With such a configuration, the enzyme reaction can be performed with a high concentration of the reaction products, even if the number of molecules of the reaction products is quite small. Thus, it is possible to detect an activity of one molecule of enzyme.
Non-Patent Literature 1 discloses a method for carrying out a single-molecule enzyme assay by use of an array where a liquid droplet is covered with oil, in a femtoliter-order, and accessible directly from the outside. This array includes a hydrophilic region pattern made of a hydrophilic surface on which a hydrophobic region having a height of 17 nm is provided.
Non-Patent Literature 2 discloses a method for detecting a protein by a single-molecule Enzyme-Linked ImmunoSorbent Assay (ELISA). According to this method, a very small amount of proteins are captured by minute beads covered with protein-specific antibodies, and complexes of the beads and the proteins are fluorescence-labeled. Then, beads including the complexes are introduced into a reaction chamber by centrifugal force. Thereafter, the number of beads having captured the proteins is counted. In this manner, the proteins are quantitatively assayed.